Fuel ignition device



United States atent [72] Inventors Otto Beesch;

Karl Wolf, Stuttgart-Sonnenberg, Germany [21] Appl. No. 766,178

[22] Filed Oct. 9, 1968 [45] Patented Nov. 3, 1970 [73] Assignee Robert Bosch GmbH Stuttgart, Germany [32] Priority Oct. 19, 1967 [33] Germany [54] FUEL IGNITION DEVlCE 10 Claims, 2 Drawing Figs.

[52] U.S. Cl 123/145,

v 123/30, 123/32, 123/139 [51] Int. Cl F02p 19/00 [50] Field ofSearch 123/30,

3,407,794 10/1968 Nagaietal 123/145(A)UX Primary Examiner-Laurence M. Goodridge Attorney- Michael S. Striker ABSTRACT: A glow plug has a housing provided with a fuel passage and a fuel inlet. Removably arranged in the fuel inlet is an adjustable throttling device consisting of two members one of which closes the inlet and is provided with an axial bore for incoming fuel. A radial bore communicates with the axial bore as well as with the fuel passage of the housing. Another member is telescoped into the axial bore downstream of the place where the radial bore communicates therewith and the effective cross section of the radial bore may be varied by sliding the two members relative to one another so that the radial bore is partly covered by an edge of the other member. Other embodiments are also described in the disclosure.

Patented Nov. 3, 1970 FIG.2

INVENTORS Otto BEESCH Karl WOLF" W/M 11M theirATTORNEY FUEL IGNITION DEVICE BACKGROUND OF THE INVENTION The present invention relates to a fuel-ignition device, and particularly to a glow plug for use with diesel engines and the like. Still more particularly the invention relates to a throttling means which is used in conjunction with such a glow plug.

It is well known that the supply of fuel to glow plugs in diesel engines and similar applications must be very precise in order to assure ready starting of the engine and proper running once started. Furthermore it is necessary that the supply of fuel be adjustable so as to provide for optimum conditions in dependence upon the operating characteristics and circumstances of different engines.

To obtain these required control possibilities glow plugs are conventionally provided with'dosing or throttling devices inserted in the inlet or passage for the fuel and consisting of a sleeve and a cylindrical needle received with clearance in the sleeve so that the gap resulting from such clearance determines the quantity of fuel which may pass through the throttling device. However, it has been found that contaminants in the fuel, including water contained therein, tend to clog the narrow gap between the needle and the inner surface of the sleeve, an occurrence which is quite frequent and which has not yet been possible to overcome.

Accordingly it is an object of our present invention to overcome this disadvantage.

More particularly it is an object of the present invention to provide in a fuel-ignition device of the type in question an adjustable throttling means with which the throughput of fuel may be precisely adjusted but which is not subject to clogging.

An additional object of the invention is to provide a device of the type in question which is simple and economical in its construction, and which requires no or little precision machining and finishing by contrast with the devices known heretofore.

SUMMARY OF THE INVENTION Pursuant to the above objects, and others which will become apparent hereafter, one feature of our invention resides In the provision of a fuel-ignition device. particularly a glow plug of the type used in diesel engines and related applications, wherein a housing is provided with a passage for combustible fuel and with an inlet which communicates with this passage. Fuel-igniting means is arranged in the housing and serves to ignite fuel which is admitted into the passage through the inlet, In accordance with the invention the device further comprises adjustable throttling means for controlling the entry of fuel into the passage and this throttling means comprises a pair of telescoped memberswhich are received in the inlet closing the same. One of these members is tubular and is provided with a radial aperture arranged to receive incoming fuel and communicating with the passage. The members are slidable with reference to one another between a plurality of positions in which the other member covers the aperture to different extents and thereby varies the effective cross section of the aperture for controlling the flow of fuel therethrough and into the passage of the housing.

With this arrangement we make it possible to utilize a radial aperture whose cross-sectional area in uncovered condition is larger than the maximum effective cross section needed for entry of the maximum permissible quantity of fuel. By having an aperture of larger cross section than necessary even under conditions of maximum fuel entry, the possibility of clogging is eliminated or at least reduced to an absolute minimum. Evidently, the manufacture of such an arrangement is also much simpler and less expensive than heretofore necessary because larger bores can be made more readily and with less precision than the small nozzle-type bores heretofore common and which always required not only precision dimensioning during the original boring operation but also precision finish- Ing.

The novel features which are considered as characteristic BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial section through a device according to the present invention illustrating the invention in one embodiment; and

FIG. 2 is an enlarged fragmentary view illustrating our adjustable throttling means in another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing first FIG. 1 of the drawing it is pointed out that we have illustrated this embodiment in conjunction with a glow plug for use with a diesel engine. How the glow plug operates is well known, just as it is well known how it cooperates with the diesel engine so that the latter is not illustrated. For the purposes of the present invention this is not believed necessary. I

The glow plug comprises a housing 10 of generally cylindrical configuration having an axial aperture in which there is received a glow pin 11 constituting the fuel-igniting means of the glow plug. The housing 10 further includes a fuel inlet nipple 12 which is carried by the housing 10 and whose inlet passage for the fuel communicates radially with the fuel passage in the housing 10. Advantageously the fuel inlet nipple 12, which will receive fuel in known manner from a nonillustrated source, may be removably connected with the remainder of the housing 10. I

The fuel passage in the housing 10 in which the glow pin ll is located is identified with reference numeral 100.

In accordance with the present invention adjustable throttling means is provided in the nipple 12. In the embodiment of FIG. 1 this throttling means consists of a tubular sleeve 13 provided with a radial aperture or bore 14 which communicates with the interior of the sleeve 13 as well as with the fuel inlet passage of the nipple 12 which constitutes a part of the fuel passage 100. A cylinder 15 is received in the forward end of the sleeve 13, and it closes this forward end. The piston member 15 is in the illustrated embodiment press fitted, but it will be appreciated that other approaches are feasible. The member 13 with the member 15 introduced thereinto is maintained in predetermined position with the inlet passage of the nipple 12 by an externally screw-threaded member 16 which is threaded into the fuel inlet passage of the nipple 12 and which is provided with an axial bore communicating with the interior of the sleeve 13. Advantageously a fuel filter 17 of known type is received in the axial bore 160 of the member 16, for instance by being press fitted therein. The interior of the fuel inlet passage of the nipple 12 is provided with a circumferential shoulder 12a and the member 16 serves to press the sleeve 13 into abutment with the shoulder 120, thus preventing intrusion of fuel into the passage 10a in any manner other than through the radial aperture or bore 14.

It will be appreciated that the effective cross section of the aperture 14 can be varied at will by sliding the member 15 between a plurality of positions in each of which it may close the aperture 14 to a different extent. In other words, the edge of the member 15 facing the aperture 14 may overlie the inner side of the aperture 14 to different extents whereby the effective cross section of the aperture 14, that is the exposed cross section which determines the passage of fuel as opposed to the cross section of the aperture 14 in unobstructed or uncovered condition, is varied. By virtue of the fact, however, that downstream of the constriction thus provided, that is downstream of the effective cross section, the cross section of the aperture 14 is not so constricted and thus corresponds to the actual cross section, clogging of the aperture 14 by contaminants in the fuel, insofar as they have not already been removed by the filter 17, is avoided because the increase in the cross section of the aperture 14 once the contaminant has managed to pass through the effective cross section determined by the edge of the piston member 15, allows such contaminants to be flushed out of the aperture 14 and into the passage a.

In the embodiment of FlG. 2 we have omitted elements which are not essential to an understanding of this embodiment. The embodiment of FIG. 2 may be simply substituted for the throttling means illustrated in FIG. 1 and all other elements may be the same as those shown in FIG. 1. This having been pointed out an examination of FIG. 2 indicates that this embodiment differs from the embodiment of the throttling means in FIG. 1 in that the piston member is replaced with a cap member 21. Unlike the embodiment of FIG. '1, however, the radial aperture or bore of FIG. 2 which corresponds. to the aperture 14 in FIG. 1, is provided not in the sleeve member 19 which corresponds to the sleeve member 13 of FIG. 1, but rather in the circumferential wall of the cap member 21. From this it follows that it is the leading edge of the projecting portion 19a of the member 19, which projecting portion 19a is received in the cap member 2!, which will perform the function of the piston member 15 of FIG. 1. ln other words, it will be the leading edge of the portion 19a which serves to vary the effective cross section of the radial aperture 20. In this embodiment it is the member 21 which may be slidably moved axially with respect to the member 19, although other possibilities for effecting sliding movement of the two members with respect to one another are of course feasible, just as is the case in FIG. 1.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others canby applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

We claim:

1. A glow plug for use with diesel engines and the like, comprising housing means provided with a passage for combustible fuel and having an inlet communicating with said passage; a glow pin in said passage for igniting fuel which is admitted into the same; and throttling means for controlling the entry of fuel into said passage, said throttling means comprising a pair of telescoped members received in said inlet closing the same. one of said members being tubular and provided with a radial aperture arranged to receive incoming fuel and communicating with said passage, and said members being stationarily positionable in a plurality of relative positions in which the other of said members covers said aperture to different ex tents, whereby the effective cross section of the aperture and the flow of fuel therethrough and into said passage are functions of the relative positions of said member.

2. A glow plug as defined in claim 1, said aperture having a cross-sectional area in excess of that required for the maximum permissible flow of fuel therethrough.

3. A glow plug as defined in claim 2, said other member having an edge portion which in different relative positions of said members covers said aperture to an extent determined by the respective position.

4. A glow plug as defined in claim 3, said one member having an axial bore having an open inlet end facing upstream with respect to the direction of fuel flow and being provided with said radial bore inwardly of said inlet end, and said other member being a piston received in and closing said axial bore inwardly of said radial bore, said piston being positionable in said axial bore in any of said plurality of positions.

5. A glow plug as defined in claim 3, said one member hav ing an axial bore having an open inlet and facing upstream with respect to the direction of fuel flow and a closed end, said radial bore communicating with said axial bore intermediate said ends, and said other member being a substantially tubular member arranged to receive incoming fuel and having a sectron received In said open inlet end, said section being provided with said edge portion,

6. A glow plug as defined in claim 2, said housing means including a fuel-inlet nipple provided with an inlet passage having said inlet, and said throttling means being removably received in said inlet passage of said fuel-inlet nipple.

7. A glow plug as defined in claim 2, said one member having an inlet aperture for fuel; and wherein said throttling means includes an externally threaded member threaded into said inlet of said housing means and maintaining said telescoped members in predetermined position in said inlet, said threaded member having a fuel bore communicating with said inlet aperture so that fuel may enter into the latter through the former.

8. A glow plug as defined in claim 7 and further comprising fuel filter means provided in said fuel bore for filtering fuel which passes therethrough.

9. A glow plug as defined in claim 2, and further comprising fuel filter means arranged in said one member upstream of said radial bore for filtering the fuel prior to entry of the same into said radial bore.

10. A glow plug as defined in claim 6, said inlet nipple being a discrete element releasably connected with the remainder of said housing means for facilitating removal and insertion of said throttling means. 

